Field of the Invention
The present invention relates to hot plug devices and circuits controlling power to a hot plug device.
Background of the Related Art
Many systems require the ability to hot plug a device into the system, and control the inrush current seen by the charging of input capacitance. In most technologies there is a balance between charging the capacitance as fast as you can so the FETs are not in a linear mode too long, and not tripping the over current of the regulator or any other upstream power supply. The main issue is where a power rail of the hot plug device has an impedance that is lower than the over current trip point, but high enough to damage a FET if turned on into this impedance. This exposes hot plug mechanisms to cases where, if there is a failure on the rail and the impedance is a soft short, severe power dissipation can occur in the turn on FETs, and can lead to a double fault causing damage in a server environment.